Aluminum is commonly used in the capacitor industry as a coating for polymer films. This is because aluminum is a light weight conductor and is easily vapor deposited. However, difficulties are encountered in bonding aluminum to the polymer surface without the need for adhesives.
Efforts have concentrated on modifying polymer surfaces by means of electric corona discharge, ion bombardment and use of various chemical etching solutions.
All of these methods suffer from serious drawbacks. Electric corona discharge requires a high voltage AC or DC electric field. Ion bombardment is directional, that is, implanted ions only enter surfaces that are in direct line and exposed to the ion beam. It is generally difficult to treat both sides of a film or irregularly shaped objects. Etching solutions are messy, have to be disposed of safely, and can be dangerous.